Tolerance develops to clinically used opioids that lead to increased doses to keep the patient in a pain-free state. As dose increases, so do undesired side effects. The present invention is based on the knowledge that delta opioid antagonists co-administered with mu agonists lessen the development of tolerance to the mu agonists (like morphine). The method comprises a new opioid analgesic (NCE) to which tolerance to analgesia develops less rapidly than morphine. The NCE has an alcohol incorporated into the 5-position of oxymorphone to give a novel compound that has the profile of a single compound with a profile of a delta antagonist and a mu agonist, and demonstrated lower tolerance than morphine in mice. This NCE, along with analogs of morphine, dihydromorphine, hydromorphone, codeine, dihydrocodeine, hydrocodone and ethylmorphine described herein, may become utilized as new analgesics with far fewer side effects than current employed opioids (morphine, oxycodone).